binary-tree-zigzag-level-order-traversal

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Algorithms

Given the <code>root</code> of a binary tree, return the zigzag level order traversal of its nodes&#39; values. (i.e., from left to right, then right to left for the next level and alternate between).

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
<pre>
Input: root = [3,9,20,null,null,15,7]
Output: [[3],[20,9],[15,7]]
</pre>

Example 2:

<pre>
Input: root = [1]
Output: [[1]]
</pre>

Example 3:

<pre>
Input: root = []
Output: []
</pre>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the tree is in the range <code>[0, 2000]</code>.</li>
	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
</ul>

zigzagLevelOrder

Binary Tree Zigzag Level Order Traversal

Binary Tree Level Order Traversal

binary-tree-level-order-traversal

二叉树的层序遍历

Zigzag Grid Traversal With Skip

zigzag-grid-traversal-with-skip

跳过交替单元格的之字形遍历

Tree

Breadth-First Search

Binary Tree

给你二叉树的根节点 <code>root</code> ，返回其节点值的 锯齿形层序遍历 。（即先从左往右，再从右往左进行下一层遍历，以此类推，层与层之间交替进行）。

&nbsp;

示例 1：
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
<pre>
输入：root = [3,9,20,null,null,15,7]
输出：[[3],[20,9],[15,7]]
</pre>

示例 2：

<pre>
输入：root = [1]
输出：[[1]]
</pre>

示例 3：

<pre>
输入：root = []
输出：[]
</pre>

&nbsp;

提示：

<ul>
	<li>树中节点数目在范围 <code>[0, 2000]</code> 内</li>
	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
</ul>